What's a good way to take maintain your respiratory system?

Crud in chest: You mean phlegm in your chest.You need to stop smoking if you smoke if you have nasal allergies to treat with antohistamines and/or nasal steroids if you have asthma you need long term bronchdilaters with inhaled steroids and you can try over the counter musinex as well we need more history to advice what applies to you see your doctor if in doubt.